2010-19-1 PedsPerspectives:06/15-2 Ped Perspectives 1/7/10 1:18 PM Page 2 APEDIATRICPerspective Volume 19, Number 1 2010 Assessing Bone Health in Children DXA Scans Play a Vital Role in Management

by Kevin Sheridan, M.D.

Providers often see bone fractures resulting from trauma. for nutrition might require calcium and vitamin D Fractures caused by osteoporosis and osteopenia occur most supplementation. often in older adults, although some children and adolescents are also at risk. In particular, children who have disabilities and Second, children who have neuromuscular and other other chronic conditions experience poor bone health as a result syndromes might require anti-seizure and steroid of their underlying disorders (e.g., neuromuscular diseases and medications. Because those medications affect the ability recurrent or chronic inflammatory disorders). of bones to model and remodel, they can lead to low bone- mineral density. Some studies have linked the seizures In those children, issues such as feeding difficulties, inadequate themselves — and not simply anti-seizure medications — to nutrition, medications (including anti-seizure and steroid a greater prevalence of fractures in both children and adults. medicines), limb contractures and an inability to perform weight- bearing exercise further contribute to abnormal bone growth and Third, neurological problems can result in skeletal bone strength. As a result, children might be more susceptible to deformities that impair bone health. For example, the high fractures and might experience a corresponding decrease in their muscle tone in cerebral palsy creates abnormal mechanical quality of life. stresses around the joints, leading to disordered growth and increased fractures. The frequency of fractures in some Primary-care providers should consider investigating, or refer to studies correlates with the degree of physical impairment: a pediatric bone specialist, if they see patients who: The greater the degree of physical compromise (e.g., spastic • Show signs of a known bone or neuromuscular disorder quadriplegia as compared to spastic diplegia), the greater the • Display inconsistent patterns of growth occurrence of fractures. Bone health becomes particularly • Sustain unexpected (fragility) fractures important when surgery is performed to correct those • Use steroid medications regularly (for conditions such as deformities. Postoperatively, healthy bones are better able rheumatoid arthritis and asthma) to heal and resist infection. • Display any form of chronic inflammation or bone deformities • Experience prolonged periods of immobilization Finally, extended periods of immobilization (e.g., after A specialist in pediatric bone conditions, such as a pediatric surgery or a fracture) increases the loss of healthy bone. endocrinologist, often is needed to diagnose such problems and In addition, secondary health problems such as recommend appropriate interventions. Imaging modalities, hyperthyroidism, rickets, growth hormone deficiency, excess including dual–energy radiograph absorptiometry (DXA) scans, lead exposure and renal problems increase bone loss or help practitioners assess the extent of bone compromise and inhibit bone growth. Genetic bone diseases (such as monitor treatments. osteogenesis imperfecta, idiopathic juvenile osteoporosis, and some inborn errors of metabolism) are less common Children at Risk causes of weakened bones and, ultimately, of fractures. Low bone-mineral density is the primary cause of compromised bone health. Many factors can contribute to low bone-mineral All of the above increase a child’s vulnerability to fractures density. from daily activities or minimal trauma. Consider referring such children to a pediatric endocrinologist if: First, a variety of nutritional issues often are associated with • They have a chronic disability, such as cerebral palsy, disabilities. For example, people who have cerebral palsy often and experience recurrent fractures. have food allergies as well. If those people must avoid dairy • They have been diagnosed with a bone condition such as products, their diets might lack sufficient amounts of calcium, osteogenesis imperfecta. phosphorus, and vitamin D — the facilitators of building strong • Their bone growth (height) lags significantly behind that bones. Even children who rely on gastrostomy tubes (G-tubes) of their chronological peers. Continued on Page 2 2010-19-1 PedsPerspectives:06/15-2 Ped Perspectives 1/7/10 1:18 PM Page 3

Evaluating Bone Density DXA technology enables health-care providers to scan bones and then calculate Gillette Makes their mineral density. Musculoskeletal Research Benefits a Priority The primary benefits of DXA scans are their precision, ease of use and low level of radiation. In comparison to the radiation of a standard chest X-ray, DXA scans Gillette Children’s Specialty Healthcare is involved emit just 10 percent of the amount of radiation. DXA scans are also more in musculoskeletal research. Gillette has sensitive than routine radiographs in detecting bone loss. For example, patients established five primary areas of focus: would have to lose 20 to 30 percent of their bone density before those losses would be apparent on an X-ray; a DXA scan can identify bone-density losses of • Bone health in children, particularly in the as little as 3 percent. presence of chronic conditions. Bone development during childhood is clearly For these reasons, DXA scans are the preferred method of following changes in altered in the presence of certain disabilities. bone-mineral density over time. A better understanding of bone health can help Limitations reduce pain, deformity, and fracture risk. DXA scans do, however, have limitations — particularly in children and teen- • Long-term consequences of conditions that agers. Bone size varies less in adults than in growing children. During the rapid growth phase of puberty, the bones grow longer before they grow wider. originate during growth and development A smaller or thinner bone might falsely appear to have a low bone-mineral and affect the musculoskeletal system. density on a DXA scan. Thus, age and puberty maturation are important Understanding the implications of childhood- considerations when interpreting DXA scans in pediatric patients. onset disabilities in adolescence and adulthood can inform treatment decisions during In children with disabilities, previous fractures, abnormally shaped bones, and childhood. surgically placed hardware all interfere with interpretations of bone-mineral density. • Effects of intervention (operative or non- operative) for conditions originating during Proper positioning of the patient for scanning the bone region of interest (hip, growth and development. spine, arm, and distal femur) is sometimes a problem in scanning people who have disabilities. Muscle contractures in the hips and arms, or scoliosis in the Intervention has the potential to change a spine, impede the ability to replicate the same position from scan to scan. If a condition’s natural progression and improve patient’s position changes between scans, the test results will indicate a false patient health. Determining whether intervention bone density change. outcomes are superior to non-intervention – and whether the intervention process is tolerable Given these difficulties, it is important to use appropriate pediatric reference — can influence treatment decisions. standards and to have the scans done at appropriate DXA centers, which are experienced in the positioning problems of people who have disabilities. • Impact of nutritional status and associated health problems on surgical treatment. Pediatric Reference Base Understanding the factors that influence Henderson1 and colleagues explored the use of alternative sites to measure postsurgical healing can help prevent bone-mineral density in children with cerebral palsy. He and his colleagues found that the lateral distal femur site was more accessible and reproducible debilitating complications and failures to achieve than other sites (at the hip, spine, and arm). Children with neuromuscular treatment goals. conditions tolerated scanning of the lateral distal femur site much better than • Role of prenatal tests and postnatal genetic scanning of other sites, and the site was more frequently free of artifacts. evaluations in conditions for which care is Henderson has published a reference database of 256 healthy children, ages 2 provided at Gillette. to 18, using the lateral distal femur site. Most of the bone-health centers that New genetic evaluations might permit a better perform DXA scans deal primarily with adults; a few also will scan the spine, hip, understanding of the natural history of some and arm of children. Gillette Children’s Specialty Healthcare is one of a limited conditions and could alter treatment planning. number of centers that offers DXA scans of the usual regions of interest in addition to lateral distal femur sites. Gillette uses pediatric reference data for all sites, including the distal femur site.

2 2010-19-1 PedsPerspectives:06/15-2 Ped Perspectives 1/7/10 1:18 PM Page 4

Treating Low Bone Mineral Density Once low bone mineral density is identified, the next question is: Author’s What treatments are appropriate and effective? Profile At Gillette, the first step is to review a patient’s nutritional status and use of medications; we then make alterations, if necessary. Sometimes simply improving the amount or composition of the diet, addressing vitamin or mineral deficiencies, or changing medications can be enough to improve bone density. The U.S. Department of Health and Human Services2 estimated that a 10-percent increase in bone mass can reduce fracture risk by as much as 50 percent in adults.

Decreasing the potential for falls and stabilizing limbs in children who have cerebral palsy and other disabilities reduce the likelihood of fractures. Weight-bearing activities, when possible, strengthen bones and improve balance. Although studies have looked at the effects of standers and vibration platforms on bone-mineral density, more studies are needed to determine whether changes in bone-mineral density correspond to decreased fractures.

Other treatment options include administering medications that diminish the breakdown of bone. Bisphosphonates, such as pamidronate, have Kevin Sheridan, M.D. been shown to temporarily decrease fracture rates in some children. Other bisphosphonates commonly used in postmenopausal osteoporosis , M.D., is a pediatric endocrinologist are oral risendronate, alendronate, ibandronate or intravenous Kevin Sheridan zolendronate. Those medications have been less well-studied in at Gillette Children’s Specialty Healthcare in children, especially children who have disabilities. In addition, much less St. Paul, Minn. He also provides internal medicine is known about the long-term effects of the medications when begun in and general pediatric services to Gillette patients. childhood. Complications such as adynamic bone are a concern, but Sheridan has a special interest in the role of rarely seen. Use of bisphosphonates around the time of surgeries might preventive health care for people of all ages who also compromise bone healing. Sometimes, however, the benefits may have chronic conditions. outweigh the uncertain risk in patients who sustain frequent fractures (e.g., patients who have osteogenesis imperfecta). A few studies have examined the effectiveness and side effects of growth-hormone treatment He graduated from the University of Minnesota in children with cerebral palsy. Medical School and completed a fellowship in pediatric and adult endocrinology there. Conclusion Life expectancy is increasing for people who have disabilities and many chronic conditions. At the same time, the osteoporosis that elderly people experience can occur at a much younger age in adults who have disabilities — especially if those adults experienced compromised bone health during childhood. Compromised bone health is associated with increased morbidity and mortality in elderly adults. Therefore, bone health is becoming an important determinant of the quality of life in both children and adults who have disabilities. DXA scans can play an important role in assessing and treating bone disorders.

Resources 1 Henderson RC, Lark RK, Newman JE, et al. Pediatric reference data for dual X-ray absorptiometric measures of normal bone density in the distal femur. Am J Roentgenol 2002; 178:(2) 439-43. 2 U.S. Department of Health and Human Services. Bone Health and Osteoporosis: A Report of the Surgeon General. Rockville, Md.: U.S. Department of Health and Human Services, Public Health Service Office of the Surgeon General; Washington, D.C.; 2004.

3 2010-19-1 PedsPerspectives:06/15-2 Ped Perspectives 1/7/10 1:18 PM Page 1

Nonprofit A PEDIATRIC Organization U.S. Postage Perspective P A I D St. Paul, MN 200 University Ave. E. Permit No. 5388 Volume 19, Number 1 2010 St. Paul, MN 55101 651-291-2848 TTY 651-229-3928 A Pediatric Perspective focuses on specialized topics in pediatrics, orthopaedics, neurology and 800-719-4040 (toll-free) www.gillettechildrens.org rehabilitation medicine.

To subscribe to or unsubscribe from A Pediatric Perspective, please send an e-mail to [email protected].

Editor-in-Chief...... Steven Koop, M.D. Editor...... Lynne Kuechle Designer...... Kim Goodness Photographers...... Anna Bittner ...... Paul DeMarchi

Copyright 2010, Gillette Children’s Specialty Healthcare. All rights reserved.

Referral Information Moving Forward in the Treatment Gillette accepts referrals from physicians, community professionals and outside of Pediatric Neurological Disorders agencies. To schedule an outpatient appoint- ment, contact New Patient Services at May20-22,2010 651-290-8707, Monday through Friday Minne apolisConventionCenter,Minneapolis,Minn. between 8 a.m. and 5 p.m. Physicians who are on staff can admit patients by calling 651-229-3890. Thecourseisintendedtoincreaseproviders’understandingofadvances inresearch,diagnosesandtreatmentinterventionsforpediatric New Patient Services 651-290-8707 neurologicaldisorders.Day1willfocusoncongenitaldisabilities; Day2willfocusonacquireddisabilities;Day3willfocusoncognitive Center for Cerebral Palsy 651-290-8712 development,executivefunction,andethicalissuesrelatedtopediatric Center for Craniofacial Services 651-325-2308 neurosciences. Center for Gait and Motion Analysis 651-229-3868 Center for Pediatric Neurosciences 651-312-3176 Theconferenceisintendedforpediatricneurologists,pediatric Center for Pediatric Orthopaedics 651-229-1716 neurosurgeons,pediatricrehabilitationmedicinespecialists,pediatric orthopaedicsurgeons,primarycarephysicians,physicalandoccupational Center for Pediatric Rehabilitation 651-229-3915 therapists,speechandlanguagepathologists,nursepractitioners,nurses, Center for Pediatric Rheumatology 651-229-3893 physicianassistants,orthotistsandotherproviderswhotreatcongenital Center for Spina Bifida 651-229-3878 andacquireddisabilities. Gillette Lifetime 651-636-9443 Specialty Healthcare Ifyouhavequestionsrelatedtocoursecontent,contactSueMurr, managerofpediatricneurosciences,at651-290-8712or800-719-4040 (toll-free).Forregistrationinformation,callMaryGrimmat 651-578-5002or800-719-4040(toll-free).Toregisteronline, To obtain back issues of A Pediatric Perspective, log on to Gillette’s Web site at visitwww.gillettechildrens.org. http://www.gillettechildrens.org/default.cfm/PID=6 1.7.8.1. Issues from 1998 to the present are available.